1. Field of the Invention
The present invention relates to an electron microscope.
2. Description of the Prior Art
In the semiconductor industry, electron microscopes have been used for inspection of a large number of wafers, devices. Recently, electron microscopes for inspection in the production of various kinds and small number of devices are desired. In these fields, the use of many small sized electron microscopes for saving spaces that are arranged to distributes their sharing in accordance with purchase orders is more advantageous than the use of a single large scale electron microscope from the view point of the total cost.
Therefore, electron microscopes of space-saving and better portability that can be operated without troublesome preparation for operation have been strongly desired. In the fields of medical treatment and food industry, where needs for electron microscopes are growing, quick inspection and diagnosis by means of electron microscopes are demanded. The ultimate use of the electron microscopes is to carry out the inspection or diagnosis at sites of the industry or medical treatment, etc.
It is expected that needs for downsized electron microscopes will be increased in a custom semiconductor device industry, medical treatment, and a food industry. A downsized electron microscope was put on the market under the trade name of xe2x80x9cMicro Televisionxe2x80x9d 1970s. Further, U.S. Pat. No. 5,442,183 discloses an electron microscope whose height between the electron beam gun and the sample holder is only about 200 mm.
However, the weight of the electron microscope of Micro Television including a vacuum container, a vacuum pump, a display, etc was about 84 kg. That is, the above-mentioned electron microscope is too large to bring it to the sites in view of the size and weight. Thus, the inspection and diagnosis at sites was quite difficult as a matter of fact.
Further, a short start-up time is important for the downsized electron microscope. Since a power source is not always available during the transportation of the electron microscope to the sites, shortening of the start-up time from the state of the device in the air opened until the start of the time of inspection or diagnosis is quite important for the practical use.
Although the above-mentioned Micro Television is relatively a small sized electron microscope, the device is not easy for transportation because of its weight and it has a problem of star-up time. Similarly, though the electron microscope disclosed in U.S. Pat. No. ""183 is downsized as to the electron emitter, the vacuum container and the sample holder, transportation or portability of the electron microscope is not considered at all. Thus, it may be difficult to use this electron micro scope at sites.
Although electron microscopes have been used in various industries, there are users or operators who feel burdensome if they are not accustomed to the electron microscopes. This may be a factor to hinder the electron microscopes from exploiting the users. Thus, from the view point of exploitation of human resources, an increase in user friendliness for ordinary people or non-skilled persons is expected.